The clamp is certainly a problem in the optical design. My intension are about the use or maintance, the way the deco is used now is pulling and open the deco, then starting the engine wjile pulling the öever to close the valve again.

The setup I mentioned and is used for Rotax engines for example is one action, a spring holds permanently the valve closed, by pulling the lever you open the the valve, when you loose grip to the lever the valve will automatical close again. Isn't this much more comfertable and easier to use?

The clamp is certainly a problem in the optical design. My intension are about the use or maintance, the way the deco is used now is pulling and open the deco, then starting the engine wjile pulling the öever to close the valve again.

The setup I mentioned and is used for Rotax engines for example is one action, a spring holds permanently the valve closed, by pulling the lever you open the the valve, when you loose grip to the lever the valve will automatical close again. Isn't this much more comfertable and easier to use?

AHH! I understand what you were referring to. You are misunderstanding how the valve works. It closes by itself once the engine fires (or you release the lever while kicking) From the compression/combustion pressure. Pulling the lever opens the valve.

I hope this mechanism works (closes) well without any spring. When the spring is loosing tension it will get spitty around the deco in my experience, (This happend after a decade or so). They also have the tendency too loosen. I therefore check them once or twice a year if they still sit thight.

I hope this mechanism works (closes) well without any spring. When the spring is loosing tension it will get spitty around the deco in my experience, (This happend after a decade or so). They also have the tendency too loosen. I therefore check them once or twice a year if they still sit thight.

It closes too well, I needed to add the cable as light kicking was causing it to close before I wanted.

The valve is the standard Sthil type saw valve that is used in everything from chain saws to Harley Davidson V-twins. It has a detent that engages in the closed position to assist closing and keep it closed. This is the specific valve recommended by the Cr500 community.

Also the valves themselves are only $12, so if needed can be replaced (or spares kept) cheaply.

I managed to get the cases back together, The silencer changed to a 1.25" core, and a new outlet in the head.

Hi.i m doing a cr500 ktm project too. 94 engine with a sxf 450 2008 frame. It s welded painted put together almost completly. I m waiting for the air boot and griphics. I notice that the cdi u r using ( the part attached to the frame and connected to the spark plug) is not the original one and fit perfect on the frame mount. Where does it come from? Also my brake pedal is a little too close from the case, did u have to bend it too? I really like ur blog it help me a lot on my builng. I should have it running next week end. My engine was nothing like urs, just did top end. I also have different radiators, from a xc i think, so i ll run some different hose and use the two holes on the head. I didnt have to mod much the pipe and silenceur either. Lucky on that one. Thx

AHH! I understand what you were referring to. You are misunderstanding how the valve works. It closes by itself once the engine fires (or you release the lever while kicking) From the compression/combustion pressure. Pulling the lever opens the valve.

I only manually closed it in the video to show it's operation.

There is no real need for a lever at all surely? Guy I know uses chainsaw de-compressor valves on large capacity 4T MX bikes, and once the valve is set it closes automatically when the motor starts.

There is no real need for a lever at all surely? Guy I know uses chainsaw de-compressor valves on large capacity 4T MX bikes, and once the valve is set it closes automatically when the motor starts.

The compression is so high it closes the valve before the bike fires. I could modify the valve to stay open longer however I wanted a lever to remove the need to "find" the decomp every time I want to start it. It also makes bump starting after a stall very easy.

Hi.i m doing a cr500 ktm project too. 94 engine with a sxf 450 2008 frame. It s welded painted put together almost completly. I m waiting for the air boot and griphics. I notice that the cdi u r using ( the part attached to the frame and connected to the spark plug) is not the original one and fit perfect on the frame mount. Where does it come from? Also my brake pedal is a little too close from the case, did u have to bend it too? I really like ur blog it help me a lot on my builng. I should have it running next week end. My engine was nothing like urs, just did top end. I also have different radiators, from a xc i think, so i ll run some different hose and use the two holes on the head. I didnt have to mod much the pipe and silenceur either. Lucky on that one. Thx

You mean the coil (not the CDI) the coil is the stock KTM, with a 2t plug cap.